i would say slugs.....12 gauge though, lol.....
it's just more of a punch......i have taken hogs with both...i prefer a slug, but ol sis talked me into the buck shot......so what i do now is put the buck shot in , then i back it up with the slugs , just in case

i just wanted to add,Georgetownboys , is definately correct, you want them the close.....my second hog ever i shot about 15 yards , that bad boy came running straight at me full steam, scared me to death, first time using buck shot....but he went down not too far from me......it's an awesome experience.......